Las Vegas
— It draws busloads of Sin City tourists, it's got more mirrors than the Trump Towers, and sometimes the lights are practically blinding.

But this latest marvel in the Nevada desert isn't a hotel casino. It's a solar thermal plant that provides peak power to nearby Las Vegas, one of the most unlikely places on the planet to be showing signs of environmental fervor.

On the Strip itself, not far from the canals at the Venetian and the fake volcano, thousands of hard hats are following ecofriendly building standards at the most expensive privately funded project in US history. The CityCenter condo complex has spawned "green" subcontractors and stocked the local lumberyards with sustainable timber.

The greening of Las Vegas follows a trend seen across the country. But given Vegas's reputation as a place that likes the odds stacked in its favor, it's notable that clean energy and sustainable development no longer look like risky bets.

"In general, the paradigm in Vegas has been pretty wasteful. But it's also very expensive to keep operating that way. So I'm not that surprised," says Ron Pernick, coauthor of "The Clean Tech Revolution."

State lawmakers have seeded some of the changes. Nevada is one of two dozen states requiring that a certain percentage of electricity come from renewable energy. Nevada went further: 5 percent must be solar.

That nudge, along with the sun and open space, attracted the renewable energy firm Acciona to build in Nevada. When its 64-megawatt solar thermal plant went online this summer, it became the first new one in the US since 1991.

"I would not say that Nevada is different from other states [going green], but what they understand is that they have the potential here for development in the state – they have the resources and the needs," says Gilbert Cohen, a senior vice president with Acciona.

In other words, Nevada's leaders are realizing that the state is rich not only in gold and gypsum, but in sun and steam. In the next few years, the state is projected to quadruple its geothermal power production. And solar got another boost: Ausra, a California maker of solar-thermal parts, recently announced it would locate its North American plant in Las Vegas.

But the state is also considering proposals for new coal-fired plants, says Launce Rake with the Progressive Leadership Alliance in Nevada.

"It's not like the first thing people talk about is, 'boy, we have to be environmentally sensitive,'" says Mr. Rake. "But it does indicate that when you change the law to give incentives to engage in particular behaviors, the market will respond."

Another incentive: a rebate on state sales and property taxes for construction that meets Leadership in Energy and Environment Design (LEED) standards. MGM Mirage jumped on it, announcing it would aim for LEED certification with the 68-acre, $7.5 billion CityCenter site – which involved more square footage than all LEED-certified buildings combined in the US at that time.

When fully built, MGM can expect to save money on operating costs like air conditioning and electricity within CityCenter's casino, hotels, condos, shops, and convention center. That's good for MGM, which already owns 10 hotels on the Strip and has a citywide power bill of $350,000 a day.

"Of course the tax incentives have made it an easier decision for everybody," says Cindy Ortega, senior vice president of MGM's energy and environmental services division. "But when you look at risk on something as large as CityCenter, it's more than a financial decision to do something that nobody has ever done before."

It has meant making unusual demands down the supply chains, and creating some services and supplies from scratch:

•No company in Las Vegas could recycle worksite scrap, so MGM capitalized one of its subcontractors to offer the service for CityCenter – and Vegas's future projects.

•Few low-flow bathroom fixtures had the luxury looks MGM wanted, so it worked with suppliers to design a new faucet.

•Some 10,000 workers have been trained on sustainable building practices.

"If you look at the CityCenter project, it primes the pump," says Mr. Pernick. "Not only does it perhaps provide a model for others to follow, it also helps establish the market."

But can any further development in this crowded desert really be considered green?

CityCenter marks a step in the right direction, says Lydia Ball, the regional representative of the Sierra Club. The outward – rather than upward – growth of Las Vegas is the real concern, she says. Sprawl requires more energy to move workers and water greater distances.

Whether there is enough water to add more people, experts say, depends on how it's used. Las Vegas's water usage per capita is comparatively high – but improving. Between 2002 and 2006, Las Vegas added 300,000 people, but the overall water usage dropped by 18 billion gallons.

Those gains came largely from an incentive program that paid homeowners to pull up their lawns in favor of low-water landscaping. Since the incentives began in 1999, the water authority has pulled up enough sod to roll a strip halfway around the planet. The war on grass is warranted: Lawns soak up the majority of water use in Vegas, says J.C. Davis, spokesman for the Southern Nevada Water Authority.

As for indoor water use, he says, nearly all that water gets "recycled," meaning it is captured, treated, and returned to Lake Mead. The city can then draw an equivalent amount of water from the lake.

"They call it recycling. It's been used as an excuse for them not to do anything indoors," says Heather Cooley, coauthor of a recent Las Vegas water study from the Pacific Institute in Oakland, Calif. Moving and treating indoor water gobbles up energy, she says.

The agency could also combat water wasters through aggressive pricing tiers – beyond certain thresholds, the price per gallon spikes.

The water authority is working with developers to offer "water smart" homes outfitted with high-efficiency appliances.

In a down real estate market, "going green, going water smart, and just being very energy efficient has helped" move homes, says Maria Guterman, a saleswoman for Pulte Homes.